1. Field of the Invention
The present invention relates to a method for manufacturing liquid jet heads whereby to manufacture a resin ceiling plate by means of grooving, drilling, or the like by the irradiation of laser beam. The invention also relates to an apparatus therefor.
2. Related Background Art
The liquid jet recording head, which is used for the liquid jet recording apparatus or the like that records or prints on a recording sheet by discharging ink or other recording liquid from the fine discharge ports (orifices) as flying droplets, is provided with an elemental substrate (heater board) having on it a plurality of discharge energy generating devices (electrothermal converting elements, for example) and lead electrodes therefor as well. On this elemental substrate, a resin nozzle layer (liquid flow path formation layer) is laminated to form the liquid flow paths (nozzles) and a common liquid chamber. Then, it is generally practiced to overlay on it the glass ceiling plate provided with supply tubes of recording liquid. In recent years, however, it has been developed to manufacture a liquid jet recording head in such a manner that while the glass ceiling plate is omitted, the resin ceiling plate is integrally produced with liquid flow path grooves and the common liquid chamber, together with the supply tube of recording liquid, by means of the injection molding or the like, and then, discharge ports are processed for its formation, and then, the ceiling plate is pressed to the elemental substrate by use of elastic member for the integral formation of a head. A liquid jet head of the kind makes it possible to reduce part numbers significantly, and also, makes the assembling processes simpler. Therefore, it is anticipated that the liquid jet recording heads thus developed will contribute to the considerable reduction of costs when liquid jet recording apparatuses are manufactured using such heads.
FIG. 7 shows the principal part of the liquid jet recording head that uses the resin ceiling plate formed as described above. In FIG. 7, the liquid jet recording head Eo is shown with the resin ceiling plate which is partly broken in its representation. This head is provided with an elemental substrate 101 having a plurality of electrothermal converting elements 101a serving as discharge energy generating devices, and the resin ceiling plate 102 having flow path grooves 102f each positioned on each of the electrothermal converting elements 101a, and also, the common liquid chamber 102 communicated with each of them. For the resin ceiling plate 102, there are arranged integrally, the discharge port plate 102b provided with discharge ports (orifices) each communicated with each of the flow path grooves 102f, and the cylindrical protrusion 102d provided with the liquid supply opening 102 that opens to the common liquid chamber 102c.
At first, the resin ceiling plate is formed integrally by means of the injection molding or the like, with the discharge port plate 102b and cylindrical protrusion 102d, in addition to the flow path grooves 102f and the common liquid chamber, altogether. Then, after the discharge ports 102g are processed, the resin ceiling plate 102 is positioned so as to bring each of the flow path grooves 102f to be placed exactly on each of the electrothermal converting elements 111a on the elemental substrate 101. Thus, by means of the elastic member (not shown), the ceiling plate 102 is pressed to the elemental substrate 101 to be bonded together. In this respect, the elemental substrate 101 is fixed on a base plate 104 by means of screws or some other known means, together with the printed-circuit board 103 having driving circuit provided therefor to generate electric signals to each of the electrothermal converting elements 110a.
Also, a method has been developed to manufacture the resin ceiling plate 102 in such a manner that at first, a blank (roughly molded product) is produced by means of the injection molding or the like integrally with the main body portion 102a before the flow path grooves are provided, and the discharge port plate 102b before the discharge ports 102g are formed, and then, by use of the excimer laser beam, each of the flow path grooves 102f is processed on the main body portion 102a, and likewise, each of the discharge ports 102g is drilled on the discharge port plate 102b.
In this way, with the molding formation combined with the laser processing, it becomes possible to simplify the preparation of the molding die for processing, as well as the processing itself, because it is not required for the die used for processing the ceiling plate formation to prepare any particular member additionally for the formation of flow path portion. Further, since the laser processing performs its processing in a higher precision at a shorter period of time, the resin ceiling plates are produced at lower costs, thus promoting the reduction of costs still more for the manufacture of liquid jet heads.
Then, as the laser processing apparatus used for grooving and drilling by irradiating the laser beam onto the resin blank which is produced by the injection molding, it is suitable to adopt the one that emits excimer laser. A laser processing apparatus of the kind is generally provided with an excimer laser oscillator serving as the laser light source that emits the excimer laser beam; masks having the patterns of the flow path grooves and openings; and the optical system that projects the opening patterns onto the blank of the ceiling plate by the use of the excimer laser beam.
Now, however, when drilling is made by a technique of the kind for the formation of discharge ports, the byproducts that are created at the time of laser processing and allowed to adhere to the processing surface of the ceiling plate. Then, the surface energy per hour becomes higher on the portions where the byproducts have adhered, and the resultant wettability becomes higher with respect to the recording liquid. In other words, such surface becomes hydrophilic.
In order to enhance the discharge efficiency of the recording liquid at its discharge ports of a liquid jet head, it is desirable to make them water-repellent in order to avoid any stronger interaction between liquid and resin. Particularly, if the circumference of the discharge ports (orifices) of the discharge port plate should become hydrophilic, the smooth discharge of recording liquid is hindered. As a result, image deviation may take place when recording or printing is made on a recording medium, such as recording paper sheet, or the discharge of recording liquid may be disabled, thus presenting critical problems related to the product performance. Therefore, the water-repellent resin is coated on the resin surface. Then, the coated resin is hardened by the application of beam or heat treatment to form the water-repellent layer on the resin surface. Also, depending on the resin material, such water-repellent layer is formed by evaporating the solvent that resolves such resin material or the dispersion medium that disperses it by giving heat treatment.
Therefore, it is important to prevent the resin surface energy from rising due to the byproducts created at the time of laser processing. In order to avoid the rise of resin surface energy due to the adhesion of the byproducts, that is, to prevent the surface from becoming hydrophilic, there is known a technique, such as disclosed in the specification of Japanese Patent Application Laid-Open No. 4-279356, whereby to perform heat treatment, ultrasonic rinsing, ultrasonic water flow rinsing, high pressure water flow rinsing, or the like or to repeat applying adhesive tape and peeling it off so that the byproducts adhering to the circumference of the discharge port (orifices) are removed after the grooves or holes are formed on the resin blank by the irradiation of excimer laser.
Further, as disclosed in the specification of Japanese Patent Application Laid-Open No. 4-279355, there is known a method whereby to remove byproducts in such a manner that at first, resist or the like is coated on the resin surface provisionally, and then, the byproducts are rinsed by use of developer, together with the resist, to remove them all after the grooves and holes are formed on the resin blank by the irradiation of excimer laser.
However, in accordance with the aforesaid technique, the method of removing the byproducts should give heat treatment at a high temperature for a long time such as at 120.degree. C. for an hour after having drilled holes, which serve the liquid discharge ports, by the irradiation of laser beam on the resin blank, or such method should dry the processed resin blank after rinsing it by the application of ultrasonic waves or by use of the ultrasonic water flow. Also, there is a need for a process dedicated to the removable of the byproducts if the adhesion of the byproducts on the surface of the resin blank should be removed by use of the adhesive tapes for peeling off. Also, for the method in which resist is coated in advance, and the byproducts are removed together with the resist by use of the developer, it is necessary to provide a special process to develop the resist and rinse it off after the laser processing.
As described above, therefore, the conventional techniques to remove the byproducts need one special process or another for the execution of the designated treatments, which leads to increasing the costs of manufacture, and also, taking more time in completing the required processes. These affect the production efficiency seriously, thus presenting the problems yet to be solved with respect to the extremely lowered throughput of production.